Existing thermal imagers are typically implemented with multiple infrared sensors arranged in an array to capture thermal images of a target scene. Individual infrared sensors generally exhibit pixel-to-pixel variations such that, if left uncorrected, infrared sensors receiving the same infrared radiation may exhibit significantly different output signals.
To compensate for such variations, calibration terms may be determined during factory testing. Unfortunately, such factory testing is often time consuming and expensive. Calibration terms may also be determined periodically through the use of a temperature controlled shutter. In this regard, the shutter may be used to temporarily block the array of infrared sensors. By capturing images of the shutter, individual offset values may be determined for individual infrared sensors. These individual offset values may be applied to subsequently captured thermal images of a target scene to provide substantially uniform performance for the infrared sensors. Unfortunately, conventional shutter implementations may be prone to mechanical failure. Such shutters may also increase the cost, weight, and complexity of thermal imagers.